Changlong Ye

Turning and side motion of snake-like robot

With high adaptability to environments snakelike robots offer a variety of advantages over other mobile robots. Such a robot with passive wheels has quite different mechanism in locomotion from that of other locomotion systems. We have developed a snakelike robot for rescue applications. The unit composing the snakelike robot of Shenyang Institute of Automation (SIA) is a module including actuating system and control system. To let the snakelike robot perform turning motion and compensate offset and orientation errors of the robot, we propose an amplitude modulation method and a phase modulation method based on analysis of the serpenoid curve. The side motion of the snakelike robot can also be generated by the amplitude modulation. The tracking control method is also proposed based on sensor information. Computer simulations and experimental tests are performed to show the validity of the proposed methods.

An omnidirectional mobile robot: Concept and analysis

This paper presents a novel omnidirectional wheel mechanism, referred to as MY wheel-II, based on a sliced ball structure. The wheel consists of two balls of equal diameter on a common shaft and both balls are sliced into four spherical crowns. The two sets of spherical crowns are mounted at 45° from each other to produce a combined circular profile. Compared with previous MY wheel mechanism, this improved wheel mechanism not only is more insensitive to fragments and irregularities on the floor but also has a higher payload capacity. A kinematic model of a three-wheeled prototype platform is also derived, and the problem of wheel angular velocity fluctuations caused by the specific mechanical structure is studied. The optimal scale factor (OSF) leading to a minimum of trajectory error is adopted to solve this problem. The factors influencing the OSF are investigated through simulation. In addition, the methods used for determining the OSF are discussed briefly.

Development of a 3D Snake-like Robot: Perambulator-II

Snake-like robots exhibited more advantages than conventional mobile robots on environment adaptation. They almost can move in most ill conditions including rough terrain, desert, water, cave and tree. In this paper, a 3D snake-like robot called Perambulator-II (Shenyang Institute of Automation snake-like robot II) is developed with the acquirement of powerful propulsion and high mobility. The unit of snake-like robot Perambulator-II robot named as modular universal unit (MUU) is introduced, which behaves three DOFs with a series of passive rollers around its cylinder body. Also, some considerations on mechanism design of snake-like robots are presented. And the shell shape of 3D snake-like robot according to mobility is discussed in detail. The locomotion of Perambulator-II is presented for test its performance. The experimental results are given to validate the mobility of the snake-like robot Perambulator-II.

Development of an omnidirectional mobile platform

A novel omnidirectional wheeled mechanism, named as MY wheel, is developed based on the sliced ball structure in this paper. With mutual passive motion of two sliced balls on the same one active axis, an omnidirectional motion can be achieved. The passive rotational axes of two sliced balls are inclined with 45 degree in two parallel planes, which are perpendicular to the active axis, to realize continuous contact with the ground. This wheeled mechanism also improves the wheel intensity to carry a heavy burden, which is a key problem for omnidirectional mechanism. An omnidirectional mobile platform composed of three MY wheels is developed for validating MY wheel mechanism. Kinematic analyses are presented to verify the omnidirectional movement of this platform. Experimental results show the validity of this platform.

Design and Basic Experiments of a Shape-shifting Mobile Robot for Urban Search and Rescue

The recent natural and man-made devastations have urged the research on the urban search and rescue (USAR) robot systems. This paper presents a novel shape-shifting mobile robot system named as Amoeba II (A-II) for the urban search and rescue application. It has been designed with three degrees of freedom (DOFs) and two tracked drive systems. This robot consists of two modular mobile units and a joint unit. The mobile unit is a tracked mechanism to enforce the propulsion of robot. The joint unit can transform the robot shape for getting high mobility. A-II robot not only can adapt to the environment but also can change its body corresponding to locus space. It behaves two states including the parallel state (named as II state) and the linear state (named as I state). The parallel state enables the robot with high mobility on rough ground. With the linear state the robot can climb upstairs and go through narrow space such as the pipe, cave etc. Also, the joint unit can propel the robot to roll in sidewise direction. Especially, two modular A-II robots can be connected through jointing common interfaces on the joint unit to compose a stronger shape-shifting robot, which can transform the body into four wheels-driven vehicle. Finally, the elementary experimental results validate the adaptation and its mobility

Locomotion control of a novel snake-like robot

It is essential to design a joint mechanism for snake-like robots to exhibit more mobility, no singularity and powerful actuation for many applications. By adding a series of passive wheels to the perimeter of the newly designed joint mechanism with 3 DOFs, a snake-like robot provided with the characteristic of omnidirectional mechanism can traverse rough terrain and compensate the lack of actuation due to passive wheels. The nonholonomic constraints and kinematics are analyzed as well as the redundancy. The composite motion method and grouping alternation motion control method are thus proposed for the locomotion of robot and the avoidance of singularity. Also, the grouping alternation motion adds a new explanation to the sinus lifting locomotion of natural snake. Computer simulations validate both mobility of mechanism and effectiveness of control methods.

An omnidirectional mobile robot

A novel omnidirectional wheeled mobile robot, mainly composed of three special wheeled structures-MY wheel, is developed in this paper. Based on the movement principle of sphere, the sphere of the special wheel is divided into contact part and non-contact part. The function of the omnidirectional wheel is realized utilizing the mutual complementarities of the two parts of the sphere. The passive rotational axes of two parts of the sphere are in staggered arrangement to each other at an angle of 45 degrees to realize continuous contact with the ground. At the same time, this structure also improves the strength of omnidirectional wheel. It is verified by the kinematic analysis and simulation of the wheeled mobile mechanism that the mechanism can achieve the omnidirectional movement. It is also proved by the movement experiment of the mobile robot that the omnidirectional mechanism can not only achieve the omnidirectional movements but also step over obstacles.

Modular universal unit for a snake-like robot and reconfigurable robots

A modular universal unit (MUU) is developed for snake-like robots, which has 3 d.o.f. with a series of passive rollers around its cylindrical shell. Among those d.o.f., pitching and yawing are actuated by means of differential gears to accomplish a large ratio of propulsion to mass. The series of passive rollers around the cylindrical aluminum shell of the MUU form another large wheel that can be used as a driving wheel of mobile robots. The snake-like robot composed of those MUUs has more powerful propulsion and higher mobility. By connecting MUUs in different forms, we can also realize a connected mobile platform or a manipulator in addition to a snake-like robot. Owing to it having 3 d.o.f., two or more MUUs can be connected to make up many mobile robots or form a manipulator that exhibits high mobility and agility. Some typical reconfigurable robots composed of these MUUs are analyzed for locomotion control. Finally, the locomotion experiments and simulations are given to show the characteristics of this MUU.

Coupled-drive-based joint design of a snake robot and its body-lifting method

Snake robots have very strong environmental adaptability. The locomotion and inspection of the robots depend upon their ability of climbing over obstacles and the lifting height. Especially in the rescuing application, the higher the robot can lift the more information can be obtained. A novel joint mechanism thus has been designed, that has 3 degrees of freedom among which 2 degrees of freedom are driven through a coupled drive. The snake robot composed of these joints can get a larger moment and a larger workspace. In this paper, we present the principle of the joint design that is based on a coupled drive, and introduce the lifting method of the snake robot and the effect of maximal joint angle /spl alpha/. Through analysis, we know that the number of units that the snake robot can possibly lift is the square of the number of units that the snake-like robot can directly lift. This is also confirmed by a simple example.

An in-pipe inspection robot based on adaptive mobile mechanism: mechanical design and basic experiments

A robot, which is composed of adaptive mobile mechanism, is developed for the purpose of performing the internal inspection tasks of pipelines. Adaptability and efficiency are the basic considerations for this robot. Based on these concepts, a prototype is designed and fabricated. The proposed adaptive mobile mechanism equipped with one actuator can perform two working modes, a normal working mode and an assistant enhanced mode. Robot under the normal working mode is used for moving in pipe or monitoring the inner surface of the pipe. On the other hand, robot under the assistant enhanced mode will produce a larger torque to help itself surmount an obstacle in the pipe without any other driving actuator. This special feature is achieved by applying a power transmission mechanism. The rotation problem of the stator is solved according to the calculation results of the robot kinematics. Basic experiments have been conducted to testify the adaptability and efficiency of the robot.